Humming (2008)

Jun-seo is tired of the relationship he is in with Mi-yeon. But one day she is in an accident and falls into a coma. Then, unbelievably Mi-yeon visits him the next day just like any other ordinary day. He starts searching for other traces of Mi-yeon and realizes how much he loved her. Will he discover the love he has never realized, which has always existed close by him?